Valves, namely compressor valves control fluid flow, namely gas flow, into and out of the compressor chamber. The valves are “check valves” in the sense that they permit gas flow in only one direction. Suction valves permit gas to flow into the compressor chamber, while discharge valves permit gas flow out.
Compressor valves 10, in their basic form (FIG. 1 shows a simplified cross section of a compressor valve), comprise a metal seat 100 having a plurality of passages therethrough, and a resilient plate 200 which movably engages seat 100, biased toward seat 100 by springs. The valve is spring biased closed. When plate 200 is displaced off of seat 100, fluid can flow through the valve. When plate 200 is forced against seat 100, plate 200 blocks the flow passages and therefore blocks flow through the valve. When viewed end-on, compressor valves are circular, as seen in FIG. 2.
Compressor valves are preferably tested after manufacture or repair, prior to installation into a compressor. Prior art methods included a liquid test, which placed a volume of liquid onto the plate (tending to push the plate off of the seat), to test whether the seal between the plate and the seat would withstand the weight of the water. Another method used a clamping device to pull the valve down to seal against an O-ring, after which a pressure differential could be applied across the valve seat. This method required multiple jig sizes for different size valves. All of the known prior art apparatus and methods have various disadvantages.